<div class="page-header">
    <a {% if not chart %}id="display"{% endif %} href="/cpu/">CPU 信息</a>
    <a {% if chart == 'line' %}id="display"{% endif %} href="/cpu/line">CPU 折线图</a>
    <a {% if chart == 'pie' %}id="display"{% endif %} href="/cpu/pie">CPU 饼图</a>
</div>